<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body style="background-color:black;">
    <script src="jquery.min.js"></script>
        <script type="text/javascript">
            (function($){
                $.fn.snow = function(options){
                var $flake = $('<div id="snowbox" />').css({'position': 'absolute','z-index':'9999', 'top': '-50px'}).html('❄'),
                documentHeight 	= $(document).height(),
                documentWidth	= $(document).width(),
                defaults = {
                    minSize		: 10,
                    maxSize		: 20,
                    newOn		: 1000,
                    flakeColor	: "#AFDAEF" /* 此处可以定义雪花颜色，若要白色可以改为#FFFFFF */
                },
                options	= $.extend({}, defaults, options);
                var interval= setInterval( function(){
                var startPositionLeft = Math.random() * documentWidth - 100,
                startOpacity = 0.5 + Math.random(),
                sizeFlake = options.minSize + Math.random() * options.maxSize,
                endPositionTop = documentHeight - 200,
                endPositionLeft = startPositionLeft - 500 + Math.random() * 500,
                durationFall = documentHeight * 10 + Math.random() * 5000;
                $flake.clone().appendTo('body').css({
                    left: startPositionLeft,
                    opacity: startOpacity,
                    'font-size': sizeFlake,
                    color: options.flakeColor
                }).animate({
                    top: endPositionTop,
                    left: endPositionLeft,
                    opacity: 0.2
                },durationFall,'linear',function(){
                    $(this).remove()
                });
                }, options.newOn);
                };
            })(jQuery);
            $(function(){
                $.fn.snow({ 
                    minSize: 5, /* 定义雪花最小尺寸 */
                    maxSize: 50,/* 定义雪花最大尺寸 */
                    newOn: 300  /* 定义密集程度，数字越小越密集 */
                });
            });
            </script>


</body>
</html>